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Distribution Behavior of Natural Radionuclide Pb in Molten Fe to Metal/Slag/Gas Phase

용융 Fe 중 천연방사성핵종 Pb의 금속/슬래그/가스상으로의 분배거동

  • So-Yeong Lee (Department of Materials Science and Metallurgical Engineering, Kyungpook National University) ;
  • Hyeon-Soo Kim (Korea Zinc (Department of Materials Science and Metallurgical Engineering, Kyungpook National University)) ;
  • Jong-Hyeon Lee (Korea Institute of Nuclear Safety (KINS)) ;
  • Ho-Sang Sohn (Department of Materials Science and Metallurgical Engineering, Kyungpook National University)
  • 이소영 (경북대학교 금속재료공학과) ;
  • 김현수 ((주)고려아연(경북대학교 신소재공학부)) ;
  • 이종현 (한국원자력안전기술원) ;
  • 손호상 (경북대학교 금속재료공학과)
  • Received : 2024.02.26
  • Accepted : 2024.03.29
  • Published : 2024.04.30

Abstract

When steel contaminated with Pb, produced by the decay of natural radionuclides, is remelted, Pb distributes among the metal, slag, and gas phases. In this study, 5 wt%Pb was added to Fe and melted with CaO-SiO2-Al2O3-MgO slag to investigate Pb's distribution in the metal/slag/gas. As slag basicity ((wt%CaO)/(wt%SiO2)) increased, Pb solubility in Fe slightly increased, while Pb in the slag tended to decrease. Consequently, the slag/metal distribution ratio of Pb decreased with increasing basicity. Thermodynamic calculations revealed that the slag/Fe phase distribution ratio of Pb remained very low irrespective of the activity coefficient of PbO in the slag, consistent with the experimental results. The calculated evaporation rate of Pb in Fe-Pb was approximately 22 times that of Fe; hence, most of the Pb evaporated into the gas phase.

천연방사성핵종의 붕괴에 의해 생성된 Pb에 의해 오염된 철강을 재용해하면 Pb는 금속, 슬래그, 기상으로 분배된다. 본 연구에서는 Fe 중에 5 wt%의 안정한 Pb를 첨가하고 CaO-SiO2-Al2O3-MgO계 슬래그와 함께 용융시켜 Pb의 금속/슬래그/가스상으로의 분배 거동을 조사하였다. 슬래그 염기도((wt%CaO)/(wt%SiO2))가 증가함에 따라 Fe 중 Pb 용해도는 약간 증가하는 경향을 나타내었으며, 슬래그 중 Pb는 감소하는 경향을 나타내었다. 따라서 염기도 증가에 따라 Pb의 슬래그/금속 사이의 분배비는 감소하는 경향을 나타내었다. 열역학적 계산 결과 슬래그 중 PbO의 활동도계수와 무관하게 Pb의 슬래그/Fe상 중 분배비는 매우 낮은 값으로 실험 결과와 유사한 수준을 나타내었다. Fe-Pb 중 Pb의 계산 증발속도가 Fe의 약 22배에 달하여 Pb의 대부분이 기상으로 증발되었다.

Keywords

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